W3C home > Mailing lists > Public > public-tt@w3.org > January 2015

Re: [TTML2] tts:{width,height} rename

From: Glenn Adams <glenn@skynav.com>
Date: Tue, 27 Jan 2015 11:26:22 -0700
Message-ID: <CACQ=j+cfcQAepwx9hZ9fhmgJfOQi45mfaThXCcuLsRV5wd209A@mail.gmail.com>
To: John Birch <John.Birch@screensystems.tv>
Cc: "pal@sandflow.com" <pal@sandflow.com>, "singer@apple.com" <singer@apple.com>, "public-tt@w3.org" <public-tt@w3.org>
On Tue, Jan 27, 2015 at 11:21 AM, John Birch <John.Birch@screensystems.tv>
wrote:

>  IIRC negative space in SMPTE use case is for use predominantly in the
> ibd (!)... I.e. To impact upon line spacing by bringing lines of text
> closer than font metrics dictate.
>

If that is the case, then the new tts:letterSpacing property should be used
with negative tracking to tighten the fit. Positive tracking can be used to
loosen the fit.


>
> But my memory may be faulty...
>
> Best regards,
> John
>
>  *From*: Glenn Adams [mailto:glenn@skynav.com]
> *Sent*: Tuesday, January 27, 2015 06:11 PM
> *To*: Pierre-Anthony Lemieux <pal@sandflow.com>
> *Cc*: David Singer <singer@apple.com>; TTWG <public-tt@w3.org>
> *Subject*: Re: [TTML2] tts:{width,height} rename
>
>
> On Tue, Jan 27, 2015 at 10:51 AM, Pierre-Anthony Lemieux <pal@sandflow.com
> > wrote:
>
>> > SMPTE needs to present a viable use case for such a feature
>>
>> The fact that this is a specification in use today should be
>> sufficient, a priori. In other words, ST 428-7 could be wrong, but I
>> would not assume that without clear evidence.
>>
>> > add a new issue specifically requesting negative space along with use
>> case documentation
>>
>> Hmmmm. the tts:{ipd,bpd} feature was proposed with the SMPTE liaison
>> as the sole documented requirement, but fails to meet it... so I do
>> not think closing the issue can be a reasonable course of action.
>>
>
>  I don't agree. The proposed feature handles insertion of fixed width
> space. That is the only requirement that I see as being viable here. I
> assume the opposite as you regarding negative space, i.e., that absent of
> proof of use it is a non-requirement.
>
>
>>
>> If TTWG has concerns/questions about this and other ST 428-7 features,
>> TTWG should simply collect them and ask for SMPTE's input. ITTWG can
>> incorporate SMPTE's feedback (if any) in its final disposition.
>>
>> Best,
>>
>> -- Pierre
>>
>> On Tue, Jan 27, 2015 at 9:38 AM, Glenn Adams <glenn@skynav.com> wrote:
>> >
>> >
>> > On Tue, Jan 27, 2015 at 10:33 AM, Pierre-Anthony Lemieux <
>> pal@sandflow.com>
>> > wrote:
>> >>
>> >> > correct; that use case (dubious at best) is not supported by this
>> >> > feature;
>> >>
>> >> Well... this feature is presumably in use (ST 428-7 being in use
>> >> worldwide), so I do not think TTWG can reasonably call it dubious. If
>> >> TTWG has concerns/questions, TTWG should simply ask SMPTE. In the
>> >> meantime, I have reopened ticket #237.
>> >
>> >
>> > SMPTE needs to present a viable use case for such a feature before I'll
>> > consider it; it would be better to leave 237 closed, and add a new issue
>> > specifically requesting negative space along with use case documentation
>> >
>> >>
>> >>
>> >>
>> >>
>> >> >it specifies a fixed dimension in inline or block progression;
>> >>
>> >> What does "inline dimensions" do for a <div>, which is in block
>> >> progression?
>> >
>> >
>> > every area generated by content elements has both inline and block
>> > progression dimensions; constraining the ipd of a div would constrain
>> it in
>> > the horizontal axis in a horizontal writing mode
>> >
>> >>
>> >>
>> >> Thanks,
>> >>
>> >> -- Pierre
>> >>
>> >> On Tue, Jan 27, 2015 at 9:28 AM, Glenn Adams <glenn@skynav.com> wrote:
>> >> >
>> >> >
>> >> > On Tue, Jan 27, 2015 at 10:17 AM, Pierre-Anthony Lemieux
>> >> > <pal@sandflow.com>
>> >> > wrote:
>> >> >>
>> >> >> > that is a special case of the specified feature
>> >> >>
>> >> >> The mechanism specified in the SMPTE liaison allows for negative
>> >> >> dimensions and notes "Negative values shall be allowed but should be
>> >> >> used with care as characters could overlap."
>> >> >>
>> >> >> The proposed tts:inlineLength/ipd does not allow negative
>> dimensions.
>> >> >
>> >> >
>> >> > correct; that use case (dubious at best) is not supported by this
>> >> > feature;
>> >> > you could use negative letter spacing between glyphs as an
>> alternative
>> >> >
>> >> >>
>> >> >>
>> >> >> Also, if tts:inlineLength/ipd is intended to add/substract space in
>> >> >> the inline progression, how would it work on <div>, which is in
>> block
>> >> >> progression?
>> >> >
>> >> >
>> >> > it doesn't add/subtract space; it specifies a fixed dimension in
>> inline
>> >> > or
>> >> > block progression; it applies to all content elements;
>> >> >
>> >> >>
>> >> >>
>> >> >> Thanks,
>> >> >>
>> >> >> -- Pierre
>> >> >>
>> >> >> On Tue, Jan 27, 2015 at 9:06 AM, Glenn Adams <glenn@skynav.com>
>> wrote:
>> >> >> >
>> >> >> > On Tue, Jan 27, 2015 at 10:02 AM, Pierre-Anthony Lemieux
>> >> >> > <pal@sandflow.com>
>> >> >> > wrote:
>> >> >> >>
>> >> >> >> Hi Glenn,
>> >> >> >>
>> >> >> >> Thanks for the pointer.
>> >> >> >>
>> >> >> >> The SMPTE liaison referenced in the ticker described "a
>> mechanism to
>> >> >> >> insert a variable amount of space in the middle of a rendered
>> text
>> >> >> >> string".
>> >> >> >
>> >> >> >
>> >> >> > that is a special case of the specified feature
>> >> >> >
>> >> >> >>
>> >> >> >>
>> >> >> >> Is the idea to use an empty <span> with tts:inlineLength/ipd
>> equal
>> >> >> >> to
>> >> >> >> the desired amount of space?
>> >> >> >
>> >> >> >
>> >> >> > yes
>> >> >> >
>> >> >> >>
>> >> >> >>
>> >> >> >> Why is the block progression attribute needed?
>> >> >> >
>> >> >> >
>> >> >> > symmetry
>> >> >> >
>> >> >> >>
>> >> >> >>
>> >> >> >> Thanks,
>> >> >> >>
>> >> >> >> -- Pierre
>> >> >> >>
>> >> >> >>
>> >> >> >> On Tue, Jan 27, 2015 at 8:46 AM, Glenn Adams <glenn@skynav.com>
>> >> >> >> wrote:
>> >> >> >> >
>> >> >> >> > On Tue, Jan 27, 2015 at 9:38 AM, Pierre-Anthony Lemieux
>> >> >> >> > <pal@sandflow.com>
>> >> >> >> > wrote:
>> >> >> >> >>
>> >> >> >> >> > tts:{ipd,bpd} are used to specify constraints on the
>> dimensions
>> >> >> >> >> > of
>> >> >> >> >> > areas
>> >> >> >> >> > generated by content elements
>> >> >> >> >>
>> >> >> >> >> This is in addition to region height/width, or instead, or
>> >> >> >> >> something
>> >> >> >> >> else?
>> >> >> >> >>
>> >> >> >> >> Is there a ticket related to this feature?
>> >> >> >> >
>> >> >> >> >
>> >> >> >> > not a new feature: just a name change from what was introduced
>> as
>> >> >> >> > the
>> >> >> >> > solution for ISSUE-237 [1]
>> >> >> >> >
>> >> >> >> > [1] http://www.w3.org/AudioVideo/TT/tracker/issues/237
>> >> >> >> >
>> >> >> >> >>
>> >> >> >> >>
>> >> >> >> >> Best,
>> >> >> >> >>
>> >> >> >> >> -- Pierre
>> >> >> >> >>
>> >> >> >> >> On Tue, Jan 27, 2015 at 8:12 AM, Glenn Adams <
>> glenn@skynav.com>
>> >> >> >> >> wrote:
>> >> >> >> >> > ipd = inline progression dimension
>> >> >> >> >> > bpd = block progression dimension
>> >> >> >> >> >
>> >> >> >> >> > they are the writing mode relative counterparts to width and
>> >> >> >> >> > height;
>> >> >> >> >> > the
>> >> >> >> >> > problem with the latter is that they are strongly associated
>> >> >> >> >> > with
>> >> >> >> >> > absolute
>> >> >> >> >> > axes (horizontal and vertical), while the former {ipd,bpd}
>> >> >> >> >> > don't
>> >> >> >> >> > suffer
>> >> >> >> >> > from
>> >> >> >> >> > that association
>> >> >> >> >> >
>> >> >> >> >> > it also requires less spec text and results in less
>> confusion
>> >> >> >> >> > in
>> >> >> >> >> > the
>> >> >> >> >> > spec,
>> >> >> >> >> > since in all places at present (except for line height),
>> width
>> >> >> >> >> > and
>> >> >> >> >> > height
>> >> >> >> >> > are interpreted in an absolute sense independent of writing
>> >> >> >> >> > mode
>> >> >> >> >> >
>> >> >> >> >> > tts:{ipd,bpd} are used to specify constraints on the
>> dimensions
>> >> >> >> >> > of
>> >> >> >> >> > areas
>> >> >> >> >> > generated by content elements
>> >> >> >> >> >
>> >> >> >> >> > On Tue, Jan 27, 2015 at 7:37 AM, David Singer
>> >> >> >> >> > <singer@apple.com>
>> >> >> >> >> > wrote:
>> >> >> >> >> >>
>> >> >> >> >> >> yikes
>> >> >> >> >> >>
>> >> >> >> >> >> it’s nice if the terms are readable.  Linewidth and
>> Lineheight
>> >> >> >> >> >> have
>> >> >> >> >> >> some …
>> >> >> >> >> >> recognition, albeit mostly in writing systems that use
>> >> >> >> >> >> horizontal
>> >> >> >> >> >> lines
>> >> >> >> >> >> assembled into vertical blocks.
>> >> >> >> >> >>
>> >> >> >> >> >> ipd and bpd are directions, not measurements, aren’t they?
>> and
>> >> >> >> >> >> they
>> >> >> >> >> >> don’t
>> >> >> >> >> >> exactly roll off the tongue or leap to mind in terms of
>> >> >> >> >> >> recognizability
>> >> >> >> >> >>
>> >> >> >> >> >> > On Jan 26, 2015, at 1:01 , Glenn Adams <glenn@skynav.com
>> >
>> >> >> >> >> >> > wrote:
>> >> >> >> >> >> >
>> >> >> >> >> >> > The use of width and height as writing mode relative
>> >> >> >> >> >> > properties
>> >> >> >> >> >> > is
>> >> >> >> >> >> > confusing. Change their names to ipd and bpd,
>> abbreviations
>> >> >> >> >> >> > for
>> >> >> >> >> >> > inline
>> >> >> >> >> >> > progression dimension and block progression dimension,
>> >> >> >> >> >> > respectively,
>> >> >> >> >> >> > and
>> >> >> >> >> >> > document convention that width and height (as well as
>> >> >> >> >> >> > horizontal
>> >> >> >> >> >> > and
>> >> >> >> >> >> > vertical) are always absolute and not writing mode
>> relative.
>> >> >> >> >> >> > The
>> >> >> >> >> >> > only
>> >> >> >> >> >> > exception being that 'height' in lineHeight remains
>> writing
>> >> >> >> >> >> > mode
>> >> >> >> >> >> > relative,
>> >> >> >> >> >> > i.e., specifies the nominal bpd of a line area.
>> >> >> >> >> >> >
>> >> >> >> >> >> > Change image to use tts:extent instead of the former
>> >> >> >> >> >> > tts:{width,height}
>> >> >> >> >> >> > in order to use absolute axes in expressing explicit
>> image
>> >> >> >> >> >> > dimensions.
>> >> >> >> >> >> >
>> >> >> >> >> >> > Addressed above comments in [1].
>> >> >> >> >> >> >
>> >> >> >> >> >> > [1] https://dvcs.w3.org/hg/ttml/rev/69877acd9380
>> >> >> >> >> >>
>> >> >> >> >> >> David Singer
>> >> >> >> >> >> Manager, Software Standards, Apple Inc.
>> >> >> >> >> >>
>> >> >> >> >> >>
>> >> >> >> >> >
>> >> >> >> >
>> >> >> >> >
>> >> >> >
>> >> >> >
>> >> >
>> >> >
>> >
>> >
>>
>
>
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Received on Tuesday, 27 January 2015 18:27:10 UTC

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